I have a 2000 dodge 1500 p/u 2wd. Last year, I started overheating. The temp gauge was going back and forth from red line to OK etc etc. I was able to stop and change the thermostat at work. The sensor also got replaced with it. It was good for about 2 months.

Then my water pump was leaking like an SOB. I took the day off work and changed that. I feel I did a pretty good job. By the service manual and everything

Also at the time, I had 3 leaky freezeplugs in the bottom of the block. I was able to get those changed out.

After that was all done, I started doing long distance travel for work. 500 miles at a time or so. The engine stayed as cool as normal, about a quarter inch below the 210 mark (half guage)

Now 8 months later Im still doing long distance driving but now when I start going 65-70mph my gauge goes slightly above the center line. It happened twice so I just got a coolant exchange with new thermostat and a fuel system servicing.

I still had this problem. 2 weeks later my A/C bearing went and I thought by chance this was the problem causing the serpentine belt not to run right causing the water pump to not run right etc. But, I still have this problem of riding hot. Too hot for me to be comfortable with. I smelled my exhaust and I don't smell anti freeze. The truck is 8 years old with 178000 miles.

Any suggestions of what to check without shotgunning it?

Off the top of my head I remember when my Dodge Van B-200 would run hot. My mechanic put a thermostat in that was a tad under what should have been put in degree wise and that did the trick for the van. Never ran hot again. I had that from 1976 when I bought it brand new until I was totalled in it in 1986. Another thought. You might want to check out the heater core as well. I had a heater core problem in the van and after that was fixed the van ran cooler also. It was about the same time as the thermostat was changed.